1. Technical Field
The present invention relates in general to improved communication within a multisegment local area network and in particular to improved communication within a multisegment local area network which includes mobile workstations which are coupled to the network via radio frequency transceivers. Still more particularly, the present invention relates to improved communication within a multisegment local area network which includes mobile workstations without requiring the maintenance of routing path information at each workstation within the network.
2. Description of the Related Art
Computer networks are increasingly common in the modern workplace. Such networks typically include multiple workstations and host or server devices which may be distributed over a vast geographic distance. Many different network topologies exist for interconnecting multiple computers into a distributed data processing system. One common technique for interconnecting multiple computers within a data processing network is the so-called Token Ring local area network environment. The Token Ring network environment is defined by the IEEE 802.5 standard and is well known to those having ordinary skill in the art.
In a Token Ring local area network environment, the path which data travels from one workstation to another workstation or host/server device, is established during initialization. This path is normally established by a discovery process utilizing "broadcast" messages, such as TESTS or XID. A Token Ring bridge or router device builds a path on which the broadcast frame travels by concatenating the router address with the routing information field of the broadcast messages. Thus, once a path has been established, it will not change during the duration of the communication session between elements within the network. If for some reason the path is disconnected during a communication session, the session must be terminated and a new path reestablished by re-initiating the session.
In other local area networks, devices within the network are interconnected utilizing router devices which maintain knowledge of all network interconnections. That is, the path required to traverse the network from one workstation to a second workstation, or host/server device. The logical name of a server device or workstation normally includes both the unit identification and the network identification in which the system or station is connected. During station initialization a broadcast message is also utilized to establish a path between the initializing station and the targeted system. The router device utilizes the network identification as part of the station address in order to establish a path between stations. Again, once a path is established it remains unchanged during the entire communications session.
Mobile or remote workstations are often interconnected into such networks utilizing so-called "dial up" facilities. Such workstations "call up" a local area network Gateway entity through a Public Switched Telephone Network (PSTN). As above, once such a connection has been made, the path between the workstation and the connecting host is fixed for the duration of the communications session. A mobile workstation may be allowed to relocate within the Public Switched Telephone Network (PSTN), utilizing systems which permits variance in the portion of the link from the mobile workstation to a local cellular receiving station. See for example, U.S. Pat. No. 4,984,247 and U.S. Pat. No. 4,901,340. A new connection and session must be reestablished if the workstation moves to a different location which alters the location of the link with the Public Switched Telephone Network (PSTN).
In a modern multisegment local area network, mobile workstations may be connected to host system or other workstations within the network through a radio frequency transceiver station. In a manner similar to that utilized in a cellular telephone system when the mobile workstation travels throughout the network environment, the interconnection with the mobile workstation may be changed from one radio frequency transceiver station to a second radio frequency transceiver station. In prior art system this requires the connecting path between the host system or workstation and the mobile workstation to be altered, dependent upon the new location of the mobile workstation.
Local area networks which utilize wireless connections without accessing a Public Switched Telephone Network (PSTN) are often established within corporate offices, college campuses or other similar locations. Thus, it should be apparent that a method and system whereby a mobile workstation may maintain a routing path to a host/server device or other workstation despite relocation within a multisegment local area network would be highly advantageous.